This application is based on Japanese Patent Application Nos. 11-248874 filed Sep. 2, 1999 and 11-350263 filed Dec. 9, 1999, the contents of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates generally to an electric control system for an automotive vehicle, and more particularly to an improvement in reliability of such an electric control system.
2. Discussion of Related Art
As an example of such an electric control system for an automotive vehicle, a brake control system is disclosed in JP-B2-2791964. This brake control system includes two central control devices, four brake control devices corresponding to respective four wheels of an automotive vehicle, and an input device. The input device is a sensing device including various sensors such as a brake-pedal position sensor, wheel deceleration sensors, a steering angle sensor, brake temperature sensors, brake-lining thickness sensors, braking force sensors, and wheel speed sensors. The output signals of the brake-pedal position sensor, the wheel deceleration sensors and the steering angle sensor are applied to the two central control devices, while the output signals of the brake temperature sensors, the brake-lining thickness sensors, the braking force sensors and the wheel speed sensors are applied to the four brake control devices. One of the two central control devices controls two of the four brake control devices, while the other central control device controls the other two brake control devices. Each central control device calculates a desired barking force to be generated by a wheel brake for each wheel, on the basis of the output signals received directly from the sensors, and the output signals of the corresponding brake-lining thickness sensor and wheel speed sensor, which are received from the corresponding brake control device and which represent the brake lining thickness value and the wheel speed. The central control device applies data representative of the calculated desired braking force to the brake control device, which in turn controls the wheel brake for barking the wheel, on the basis of the desired braking force data received from the central control device and the output signals of the sensors. Thus, the control of the wheel brake is partly implemented by one of the two central control device and is also partly implemented by one of the four brake control devices. The required capacity of each central control device according to this control arrangement can be made smaller that that of a central control device which is arranged to directly control the brake for each wheel. Similarly, the required capacity of each brake control device can be made relatively small and inexpensive.
The brake control system indicated above employs two power source devices one of which is adapted to supply an electric energy to the two brake control devices connected to one of the two central control devices, and the other of which is adapted to supply an electric energy to the other two brake control device connected to the other central control device. In the event where at least one of the two brake control devices which are powered by one of the two power source devices becomes defective, the supply of the electric energy to those two brake control devices is terminated, and the other two normal brake control devices are operated to control the corresponding two wheel brakes for braking the corresponding wheels of the vehicle.
However, the brake control system described above still has a room for improvement. Namely, if a sensor connected to the central control device becomes defective, for instance, the central control device cannot calculate the desired braking force, and the corresponding brake control devices become inoperable to control the wheel brakes. In the event where one of the two power source devices becomes defective, the two brake control devices connected to that defective power source device are not operable.
The control arrangement disclosed in JP-B2-2791964 is considered generally applicable to any other electric control system for an automotive vehicle, provided the electric control system includes a peripheral control device for controlling an electrically controlled actuator device, a central control device connected to the peripheral control device, and an input device whose output is by the central and peripheral control devices, which cooperate with each other to control the actuator device. In this case, too, the control arrangement has a room for improvement.
It is therefore an object of the present invention to provide an electric control system for an automotive vehicle, which includes a central control device, a peripheral control device and an input device and which is economical to manufacture and has an improved operating reliability.
The above object may be achieved according to any one of the following modes of the present invention, each of which is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) An electric control system for an automotive vehicle, including a peripheral control device for electrically controlling an actuator device, a central control device connected to the peripheral control device, and a input device, the central control device and the peripheral control device cooperating with each other to control the actuator device on the basis of an output of the input device, wherein the input device is connected to both of the central control device and the peripheral control device.
The input device may take various forms. For instance, the input device may be adapted to receive information from an external sensing device by wireless transmission or through a communication line. Alternatively, the input device may permit the operator of the vehicle to enter necessary information, or may be a sensing device adapted to detect a physical quantity or quantities and generates an output signal representative of the detected quantity or quantities. For instance, the input device includes a sensor provided according to the mode (2) of this invention, which will be described. The sensor may be a sensor adapted to detect an amount of operation of a manually operated member operable by the operator, such as a sensor provided according to the mode (3) of this invention, which will also be described. Alternatively, the sensor may be a sensor adapted to detect a physical quantity which varies irrespective of an operation by the operator, for example, a sensor adapted to detect a temperature.
In the electric control system constructed according to the above mode (1) of this invention, the input device described above is connected to both of the central control device and the peripheral control device. Where the input device consists of a single sensor, this sensor is connected to both the central control device and the peripheral control device. Where the input device consists of a plurality of sensors, at least one of these sensors is connected to both of the central and peripheral control devices.
When the central control device and the peripheral control device are both normal, the central control device and the peripheral control device cooperate with each other to control the actuator device. For example, the central control device is arranged to determine a desired amount of operation of the actuator device on the basis of the output of the input device, and supply data representative of the determined desired amount of operation of the actuator device to the peripheral control device, so that the peripheral control device controls the actuator device according to the desired amount of operation received from the central control device. Alternatively, not only the central control device but also the peripheral control device are adapted to determine the desired amount of operation of the actuator device on the basis of the output of the input device, and the peripheral control device is adapted to compare the desired amount of operation of the actuator device determined by itself, with the desired amount of operation received from the central control device, for diagnosing the peripheral control device and the central control device for any defect thereof.
When the central control device becomes defective, the peripheral control device determines the desired amount of operation of the actuator device on the basis of the output of the input device, and controls the actuator device according to the determined desired amount of operation. In this case where the central control device is defective, the electric control system is not inoperable. Thus, the present electric control system has improved operating reliability.
In addition, the central control device and the peripheral control device according to the present invention can be made relatively small in size and relatively simple in construction. In an electric control system including only a central control device and not including any peripheral control device, the central control device must function also as a peripheral control device, for dealing with various defects in the system, in order to assure the same degree of operating reliability as the present electric control system. Accordingly, the central control device of the electric control system not including the peripheral control device is inevitably complicated in construction and relatively large in size. The manufacture of this complicated, large-sized central control device requires an exclusively designed production line, causing an increase in the cost of manufacture. Further, repairing or replacing the large-sized central control device which has been found defective would require relatively a high servicing or maintenance cost. In the electric control system according to the above mode (1) of the present invention, the operating reliability is significantly improved, owing to the provision of the peripheral control device in addition to the central control device, and owing to the connection of the input device to the peripheral control device as well as to the central control device so that the peripheral control device is operable independently of the central control device. While the present electric control system uses a larger number of control devices, the required size of each control device can be reduced, so that the control devices can be manufactured at a relatively low cost by a multi-purpose production line, and can be serviced or maintained at a relatively low cost.
(2) An electric control system for an automotive vehicle according to the above mode (1), wherein the input device includes a sensor operable to generate an output signal representative of a physical quantity.
(3) An electric control system for an automotive vehicle according to the above mode (2), wherein the sensor is operable to detect at least one of an operating force and an operating stroke of a manually operated member which is operable by an operator.
The manually operated member may be a pedal or lever operable by depression thereon by an operator of the vehicle
(4) An electric control system for an automotive vehicle according to any one of the above modes (1)-(3), wherein the actuator device includes a plurality of actuators, and the peripheral control device includes a plurality of peripheral control devices connected to the plurality of actuators, respectively, and wherein the input device is connected to at least one of the plurality of peripheral control devices.
In the electric control system according to the above mode (4), at least one of the peripheral control devices is able to control the corresponding at least one actuator on the basis of the output of the input device, even when the central control device is defective.
(5) An electric control system for an automotive vehicle according to the above mode (4), wherein the input device is connected to at least two of the plurality of peripheral control devices.
In the electric control system according to the above mode (5), at least two of the peripheral control devices are able to control the corresponding at least two actuators on the basis of the output of the input device, even if the central control device is defective.
(6) An electric control system for an automotive vehicle according to the above mode (5), wherein the input device is connected to all of the plurality of peripheral control devices.
In the electric control system according to the above mode (5), all of the peripheral control devices are able to control the respective actuators on the basis of the output of the input device, even if the central control device is defective.
(7) An electric control system for an automotive vehicle according to any one of the above modes (1)-(6), wherein the input device includes a plurality of input devices whose output signals represent different kinds of information, all of the plurality of input devices being connected to the central control device and the peripheral control device.
The peripheral control device may consist of a single device or a plurality of control devices. In the above mode (7), all of the input devices are connected to the central control device and at least one peripheral control device.
In the electric control system according to the above mode (7), at least one peripheral control device is able to control the corresponding at least one actuator on the basis of the output signals of all the input devices, in the normal manner, even if the central control device is defective. The feature of the present mode (7) is available independently of the feature according to any one of the above modes (1)-(6).
(8) An electric control system for an automotive vehicle according to any one f the above modes (1)-(8), wherein the peripheral control device consists of a plurality of peripheral control devices, and the input device includes a plurality of input devices whose output signals represent a same kind of information, all of the input devices being connected to the central control device, one of the plurality of input devices being connected to at least one of the plurality of peripheral control devices while another of the plurality of input devices being connected to another of the plurality of peripheral control devices.
In the electric control system according to the above mode (8), even if the central control device and at least one but not all of the input devices are defective, the peripheral control device or devices which is/are adapted to receive the output signal or signals from the normal input device or devices is/are still normally operable. Each normally operable peripheral control device may be adapted to control only an actuator which the peripheral control device is assigned to control, or may be adapted not only to control this actuator but also supply the information received from the normal input device or devices to the other peripheral device or devices connected to the defective input device, so as to permit the above-indicated other peripheral control device or devices to be operable. When at least one of the input devices is defective while the central control device is normal, the central control device is operable on the basis of the output signal or signals received from the normal input device or devices. The feature according to the above mode (8) is available independently of the feature according to any one of the above modes (1)-(7).
(9) An electric control system for an automotive vehicle according to any one of the above modes (1)-(8), further including a plurality of power. source devices and wherein the actuator device includes a plurality of actuators, and the peripheral control device includes a plurality of peripheral control devices connected to the plurality of actuators, respectively, at least one of the plurality of power source devices being connected to at least one of the peripheral control devices while at least another of the plurality of power source devices being connected to at least another of the peripheral control devices.
In the electric control system according to the above mode (9), when one of the power source devices is defective, the peripheral control device connected to this one power source device is not operable, but the other peripheral control device or devices connected to the normal power source device or devices is/are operable, so that the electric control system is not wholly inoperable. The feature according to the above mode (9) is available independently of the feature according to the above mode (1).
(10) An electric control system for an automotive vehicle according to any one of the above modes (1)-(9), further including at least two power source devices which are mutually independently connected to the input device.
In the electric control system according to the above mode (10), when at least one of the at least two power source devices is defective, the input device is operable with an electric current supplied from the normal power source device or devices. The at least two power source devices in the present electric control system may be at least two of the plurality of power source devices provided in the electric control system according to the above mode (9). The feature according to the above mode (10) is available independently of the feature according to any one of the above modes (1)-(9).
(11) An electric control system for an automotive vehicle according to any one of the above modes (1)-(10), further including at least two power source devices which are mutually independently connected to the central control device.
In the electric control system according to the above mode (11), even when one of the at least two power source devices is defective, the central control device is operable with an electric current supplied from the other power source device or devices. The at least two power source devices in the present electric control system may be at least two of the plurality of power source devices provided in the electric control system according to the above mode (9), and/or the at least two power source devices provided in the electric control system according to the above mode (10). The feature according to the above mode (11) is available independently of the feature according to any one of the above modes (1)-(10).
(12) An electric control system for an automotive vehicle according to the above mode (11), wherein the central control device includes a main computer for controlling the actuator device, and a monitoring computer for diagnosing the main computer, each of the at least two power source devices being connected to both of the main and monitoring computers.
In the electric control system according to the above mode (12), the monitoring computer is adapted to diagnose the main computer for any defect thereof. When the main computer is defective, the central control device informs the peripheral control device that the main computer is defective, so that the peripheral control device is able to control the actuator device on the basis of the output of the input device.
Even if at least one but not all of the at least two power source devices is defective, the main and monitoring computers are both operable so that the main computer is able to control the actuator device while the monitoring computer is able to diagnose the main computer. As described above, the peripheral control device is provided as well as the central control device, and the input device is connected to the peripheral control device as well as the central control device, so that the peripheral control device is operable independently of the central control device, in the event where the central control device becomes defective. To this end, the central control device uses the monitoring computer to diagnose the main computer which is normally assigned to control the actuator device. With the provision of the peripheral control device, the number of computers required to be incorporated in the central control device can be reduced. For instance, the central control device may use only the main computer and the monitoring computer. Thus, the central control device can be reduced in size. The feature according to the above mode (12) is available independently of the feature according to any one of the above modes (1)-(10).
(13) An electric control system for an automotive vehicle according to the above mode (11), wherein the central control device includes a plurality of computers capable of performing a same function, each of the at least two power source devices being connected to the plurality of computers.
In the electric control system according to the above move (13), the plurality of computers are operable even if at least one but not all of the at least two power source devices is defective. Since the plurality of computers are capable of performing the same function, the central control device is operable even if at least one but not all of the power source devices is defective. Further, the plurality of computers are able to diagnose each other by comparison of desired amounts of operation of the actuator device determined by the respective computers. Even if at least one but not all of the computers is defective and the computers cannot be diagnosed by each other, the peripheral control device to which the input device is connected is able to determine the desired amount of operation of the actuator device on the basis of the output of the input device. By comparing the desired amount of operation determined by the peripheral control device with that determined by the central control device, the peripheral control device is able to diagnose the central control device to see if the central control device is defective or not. Since the peripheral control device is capable of controlling the actuator device in the event where the central control device is defective, the central computer need not be large-sized to deal with any defect thereof. Accordingly, the central control device can be made relatively small in size, though it includes the two or more computers.
(14) An electric control system for an automotive vehicle according to any one of the above modes (1)-(13) further including a plurality of power source devices, and wherein the actuator device includes four actuators in the form of four brakes constructed to brake a front left wheel, a front right wheel, a rear left wheel and a rear right wheel of the automotive vehicle, respectively, and the peripheral control device includes four brake control devices operable to control the four brakes, respectively, at least one of the plurality of power source devices being connected to the two brake control devices corresponding to the front left and rear right wheels which are located diagonally with respect to each other in the automotive vehicle, at least another of the plurality of power source devices being connected to the two other brake control devices corresponding to the front right and rear left wheels which are located diagonally with respect to each other in the automotive vehicle.
The brakes may be electrically or hydraulically operated brakes. Each electrically operated brake may be constructed to include, for example, a drive source in the form of a rotary electric motor, a presser member movable by the electric motor, and at least one friction member which is forced by the presser member onto a rotor rotating with the corresponding wheel of the vehicle, for braking the wheel. In this case, the brake control device controls the amount of operation of the electric motor on the basis of an amount of operation of a brake operating member. The presser member may be either a linearly movable member or a rotary member.
Each hydraulically operated brake may be constructed to include, for example, a fluid-operated actuator in the form of at least one hydraulic cylinder operated by a pressurized fluid supplied from a hydraulic pressure source, and at least one friction member which is forced by the at least one hydraulic cylinder onto a rotor rotating with the corresponding wheel of the vehicle, for braking the wheel. The hydraulic pressure source may be a master cylinder, or an electrically operated hydraulic power source including a hydraulic pump and an accumulator. Where the electrically operated hydraulic power source is used as the hydraulic power source, the brake control device may be arranged to control a solenoid-operated control valve device for regulating the pressure of the fluid pressurized by the hydraulic power source, to a level corresponding to the amount of operation of the brake operating member, so that the controlled fluid pressure is applied to the hydraulic cylinder. Where the master cylinder is used as the hydraulic pressure source, the brake control device may be arranged to control a solenoid-operated control valve device for controlling the fluid pressure in the hydraulic cylinder, in an anti-lock control fashion, for instance.
In the electric control system according to the above mode (14), one of the two sets of brake control devices which corresponds to the respective two sets of diagonally located vehicle wheels is operable even if at least one but not all of the plurality of power source devices is defective. Since the two sets of brake control devices are arranged to control the respective two sets of brakes corresponding to the respective two sets of diagonally located vehicle wheels, the braking force can be suitably distributed to the left and right vehicle wheels and the front and rear wheels. However, it is possible that the two brake control devices are provided for controlling the respective two brakes for the front left and right wheels, while the two other brake control devices are provided for controlling the respective two brakes for the rear left and right wheels. This arrangement may be better in some cases or for specific braking purposes.
(15) An electric control system for an automotive vehicle according to any one of the above modes (1)-(14), wherein the actuator device includes four actuators in the form of four brakes constructed to brake a front left wheel, a front right wheel, a rear left wheel and a rear right wheel of the automotive vehicle, respectively, and the peripheral control device includes four brake control devices operable to control the four brakes, respectively, at least two of the four brake control devices being connected to each other, and wherein when the central control device is defective, one of the at least two brake control devices connected to each other controls an operation of at least another of the at least two brake control devices.
In the electric control system according to the above mode (15), one of the above-indicated at least two brake control devices connected to each other operates, for example, to determine the same desired amount of operation of the two brakes corresponding to the above-indicated one brake control device and another of the at least two brake control devices, when the at least two brake control devices are normally operable to control the corresponding brakes and when the input device is normal. Namely, one of the at least two brake control devices operates to determine the desired amount of operation of the brake corresponding to another of the at least two brake control device such that the desired amount of operation of that brake is equal to that of the brake corresponding to the above-indicated one brake control device. Where the two brakes correspond to the front left and right wheels, the above arrangement permits even distribution of the braking force to the two front wheels and even braking of the front wheels. The desired amount of operation of one brake determined by one of the above-indicated at least two brake control devices may be used for the two brakes. Alternatively, the same desired amount of operation of the two brake may be determined by obtaining an average of the desired amounts of operation determined by the two brake control devices.
The input device may include a plurality of input devices connected to the plurality of brake control devices. When the input device to which one of the above-indicated at least two brake control devices is connected is defective, another of the at least two brake control devices may operate to supply the output of the input device received from the normal input device to the above-indicated one of the at least two brake control devices, or supply the determined desired amount of operation of the corresponding brake to the above-indicated one of the at least two brake control devices.
Where one of the above-indicated at least two brake control devices is not operable to control the corresponding brake due to a defect of a computer thereof, another of the at least two brake control devices which is normally operable may be operated to control the brake corresponding to the above-indicated one of the at least two brake control devices. The feature according to the above mode (15) is available independently of the feature according to any one of the above modes (1)-(14).
(16) An electric control system for an automotive vehicle according to the above mode (15), wherein the at least two brake control devices connected to each other consist of two brake control devices for controlling the brakes for braking the front left and right wheels.
In a braking system for an automotive vehicle, the brakes for the front wheels are generally constructed to produce a larger braking force than the brakes for the rear wheels. The arrangement according to the above mode (16) assures improved operating reliability of the front wheel brakes which are more important than the rear wheel brakes.
(17) An electric control system for an automotive vehicle according to the above mode (15) or (16), wherein each of the above-indicated at least two brake control devices connected to each other is connected to the central control device.
(18) An electric control system for an automotive vehicle according to any one of the above modes (1)-(17), wherein the actuator device includes four actuators in the form of four brakes constructed to brake a front left wheel, a front right wheel, a rear left wheel and a rear right wheel of the automotive vehicle, respectively, and the peripheral control device includes four brake control devices operable to control the four brakes, respectively, and wherein the two brake control devices for controlling the two brakes for braking the front left and right wheels are connected to the central control device, the input device being connected to each of the two brake control devices.
In the electric control system according to the above mode (18), the two brake control devices for the front left and right wheels are operable to control the corresponding two front wheel brakes even when the central control device is defective. (19) An electric control system for an automotive vehicle according to any one of the above modes (1)-(13), wherein the actuator device includes two actuators in the form of two rear-wheel brakes constructed to brake a rear left wheel and a rear right wheel, respectively, and the peripheral control device includes a common rear-brake control device for controlling the two rear-wheel brakes.
In the electric control system according to the above mode (19), the two rear-wheel brakes are not operable when the common rear-brake control device is defective. In this case, the two front-wheel brakes are operable to brake the front left and right wheels, so that the vehicle can be braked without a significant loss of running stability of the vehicle. In this respect, it is noted that the front-wheel brakes are generally arranged to produce a large braking force than the rear-wheel brakes. This arrangement results in a reduced amount of reduction of the total vehicle braking force when the two rear-wheel brakes are not operable, making it possible to brake the vehicle with an increased degree of stability by the front-wheel brakes only. The electric control system according to the above mode (19) requires a smaller number of brake control devices, and is simpler in arrangement and available at an accordingly reduced cost, while assuring a sufficient vehicle braking force without a significant loss of braking stability even when the two rear-wheel brakes are not operable.
(20) An electric control system for an automotive vehicle according to the above mode (19), wherein the actuator device further includes two actuators in the form of two front-wheel brakes constructed to brake a front left wheel and front right wheel, respectively, and the peripheral control device further includes two front-brake control devices for controlling the two front-wheel brakes.
In the electric control system according to the above mode (20), when one of the two front-brake control devices is defective, one of the two front-wheel brakes which corresponds to the other normal front-brake control device is operable, even while the rear-brake control device is also defective.
(21) An electric control system for an automotive vehicle according to the above mode (19 or (20), wherein the rear-brake control device includes an independent rear-brake control portion operable to control the two rear-wheel brakes in respective different manners.
In the electric control system according to the above mode (21), the independent rear-brake control portion of the rear-brake control device controls the two rear-wheel brakes in the different manners while the braking system including the two front-wheel brakes and the two rear-wheels brakes is normal, and/or while the braking system is defective. While the braking system is normal, the independent rear-brake control portion controls the two rear-wheel brakes independently of each other in an anti-lock control fashion, a traction control fashion, or a vehicle running stability control fashion, for example. The independent rear-brake control portion may control the two rear-wheel brakes independently of each other in desired control fashions other than the anti-lock, traction and vehicle running stability control fashions. While the braking system is defective, for instance, while one of the front-wheel brakes is defective, the independent rear-brake control portion control one of the two rear-wheel brakes in the normal manner, and inhibits an operation of the other rear-wheel brake, or control this other rear-wheel brake so as to produce a predetermined percentage of the nominal braking force which is to be produced while the braking system is normal.
(22) An electric control system for an automotive vehicle according to any one of the above modes (19)-(21), wherein the rear-brake control device includes a common rear-brake control portion operable to control the two rear-wheel brakes in a same manner.
In the electric control system according to the above mode (22), the common rear-brake control portion of the rear-brake control device controls the two rear-wheel brakes in the same manner while the braking system including the two front-wheel brakes and the two rear-wheel brakes is normal, and/or while the braking system is defective. While the braking system is normally operating to control the brakes in the normal control mode (not in the special control modes such as the anti-lock control mode), the common rear-brake control portion may control the two rear-wheel brakes so as to provide the same braking force which is determined on the basis of an amount of operation of a brake operating member. Where the braking system is normally operating to control the rear-wheel brakes in the anti-lock control mode, for example, the common rear-brake control portion may control the two rear-wheel brakes so as to provide the same braking force, which is determined by a smaller one of the desired amounts of operation of he two rear-wheel brakes which have been obtained depending upon the slipping tendencies of the two rear wheels. Where the two front-wheel brakes are defective, for instance, the common rear-brake control portion may controls the two rear-wheel brakes so as to provide the same braking force while the two rear-wheel brakes are both normal. In this case, the independent rear-brake control portion indicated above may control the two rear-wheel brakes so as to provide different braking forces.
(23) An electric control system for an automotive vehicle according to any one of the above modes (19)-(22), wherein the rear-brake control device includes a one-rear-brake control portion operable to operate one of sad two rear-wheel brakes when the other of the two rear-wheel brakes is defective.
In the electric control system according to the above mode (23), the vehicle can be braked by one of the two rear-wheel brakes even when the other rear-wheel brake is defective.